fix: 删除bot后重置activeBotId，编辑立即更新名称，config fetch await防空值

1. 删除活跃bot后将activeBotId置null，由fetchBots自动选新的
2. updateBot同时更新内存中的name（无需重启即可看到名称变化）
3. openEditBot改为async await config请求，失败时用bot名称做fallback

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/bot/instance.ts

@@ -43,7 +43,7 @@ export interface BotStatus {
 
 export class BotInstance extends EventEmitter {
   readonly id: string;
-  readonly name: string;
+  name: string;
 
   private tsClient: TS3Client;
   private player: AudioPlayer;